Insulator and manufacturing method thereof, and stator for electric rotating machine

ABSTRACT

A stator for a motor includes a stator core, an insulator, and coils. The stator core includes an annular portion and teeth, which extend radially from the annular portion. The stator core is divided into core segments in the circumferential direction. Each core segment has an arcuate portion and one of the teeth, which extends from the arcuate portion. The insulator insulates each coil wound around one of the teeth from the stator core. The insulator includes coupling portions at positions corresponding to the circumferential ends of the arcuate portions. Each coupling portion couples the adjacent core segments to be rotatable relative to each other. The insulator facilitates manufacture of the stator.

BACKGROUND OF THE INVENTION

The present invention relates to an insulator for insulating the core ofan electric rotating machine from coils wound around the core and amethod for manufacturing the insulator. The present invention alsopertains to a stator for an electric rotating machine.

A typical stator of an electric rotating machine such as a brushlessmotor, includes a core, which has teeth, and coils each wound around oneof the teeth. The core has an annular portion and the teeth extend fromthe annular portion radially toward the center of the annular portion.Each coil is wound around one of the teeth with an insulator arranged inbetween.

As an example of such a core, a core that is formed by coupling severalcore segments in annular form has been proposed. Each core segmentincludes a tooth and is formed by laminating thin plate-like piecemembers. A coil is wound around the tooth of each core segment beforecoupling the core segments with one another. Therefore, a coil is easilywound around a tooth without interfering with the adjacent teeth.

In a stator disclosed in Japanese Laid-Open Patent Publication No.7-222383, each core segment is formed by alternately laminating firstpiece members and second piece members. Each core segment has an arcuateportion, which forms part of the annular portion of the core. At thecircumferential ends of the arcuate portion of each core segment, theends of each first piece member and the ends of each second piece memberare displaced in the circumferential direction. Therefore, thecircumferential ends of the arcuate portion of each core segment have ashape in which recesses and projections are alternately arranged. Eachof the circumferential ends of each core segment is coupled to thecorresponding circumferential end of the adjacent core segment with apin so that the annular core is obtained when all the core segments arecoupled to one another. In a state where the projections of one of theadjacent core segments are fitted to the recesses of the other coresegment, that is, in a state where the projections of the adjacent coresegments overlap one another in the axial direction, a pin is insertedthrough the overlapped projections. In such a core, the adjacent coresegments are reliably coupled to each other without forming a space inbetween. This reduces magnetic resistance at the annular portion andforms a reliable magnetic circuit. Also, since the projections overlapone another in the axial direction, the coupled core segments areprevented from being displaced in the axial direction.

When manufacturing the stator, a coil is wound around each separate coresegment before coupling the core segments with one another with thepins. After winding each coil to the corresponding core segment, thecore segments are coupled to one another with the pins. This makes themanufacturing process for the stator difficult and complicates handlingof the core segments. The pins used for coupling the core segmentsincrease the number of components.

Japanese Laid-Open Patent Publication No. 2002-247788 discloses aninsulator attached to each of the core segments. The insulatorcorresponds to one core segment and is separate from an insulatorattached to another core segment. Before winding a coil about each coresegment, the insulator is attached to each core segment. This makes themanufacturing process for the stator difficult and increases themanufacturing time and the manufacturing cost.

SUMMARY OF THE INVENTION

Accordingly, it is an objective of the present invention to provide aninsulator that facilitates manufacture of a stator for an electricrotating machine.

Another objective of the present invention is to provide a method formanufacturing the insulator easily.

A further objective of the present invention is to provide a stator foran electric rotating machine that is easily manufactured.

To achieve the foregoing and other objectives and in accordance with thepurpose of the present invention, an insulator for attachment to a corehaving an annular portion and a plurality of teeth is provided. Theteeth extend radially from the annular portion. The core is divided intoa plurality of core segments in the circumferential direction. Adjacentcore segments are permitted to rotate relative to each other. Theinsulator is for insulating a coil wound around each tooth from thecore. The insulator includes a plurality of coupling portions. Eachcoupling portion couples the adjacent core segments so as to berotatable relative to each other.

The present invention also provides a stator for an electric rotatingmachine. The stator has a plurality of core segments, an insulator, anda plurality of coils. Each core segment is formed by alternatelylaminating first piece members and second piece members. Each coresegment has an arcuate portion and a tooth extending from the arcuateportion in a direction substantially orthogonal to the arcuate portion.Each arcuate portion includes opposite circumferential ends. When thecore segments are arranged in an annular form, the arcuate portions formthe annular portion and the teeth are arranged radially. The insulatoris attached to the plurality of core segments. Each coil is wound aroundone of the teeth via the insulator. Each of the first and second piecemembers has a first end corresponding to one of the circumferential endsof the arcuate portion and a second end corresponding to the other oneof the circumferential ends of the arcuate portion. The first piecemember has an arcuate projection on the first end of the first piecemember and an arcuate recess on the second end of the first piecemember. The second piece member has an arcuate recess on the first endof the second piece member and an arcuate projection on the second endof the second piece member. When each piece member is viewed from theaxial direction, the arcuate projection forms an arcuate projectionshape and the arcuate recess forms an arcuate recess shape. When theplurality of core segments are arranged in an annular form, the arcuateprojections overlap one another at the adjacent circumferential ends ofthe arcuate portions. The insulator has a plurality of coupling portionsat positions corresponding to the circumferential ends of the arcuateportions. Each coupling portion couples the adjacent core segments so asto be rotatable relative to each other.

Further, the present invention provides a method for manufacturing aninsulator attached to a core. The core is divided into a plurality ofcore segments in the circumferential direction, and the insulatorinsulates a coil wound around each of the core segments from the core.The method includes: molding a plurality of first and second insulatingmembers each having circumferential ends, which are arranged alternatelyto form the insulator, wherein each insulating member corresponds to oneof the core segments, wherein a coupling opening is formed on eithercircumferential end of each first insulating member, wherein a couplingprojection is formed on either circumferential end of each secondinsulating member, and wherein the first and second insulating membersare molded such that each coupling opening of each first insulatingmember is axially displaced from the corresponding one of the couplingprojections of one of adjacent second insulating members; and couplingthe adjacent first and second insulating members by axially moving atleast either the first or second insulating members relative to theother one of the first and second insulating members thereby insertingeach coupling projection into the corresponding coupling opening.

Other aspects and advantages of the invention will become apparent fromthe following description, taken in conjunction with the accompanyingdrawings, illustrating by way of example the principles of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, together with objects and advantages thereof, may best beunderstood by reference to the following description of the presentlypreferred embodiments together with the accompanying drawings in which:

FIG. 1 is a partial cross-sectional view illustrating a brushless motoraccording to a first embodiment of the present invention;

FIG. 2(a) is a plan view illustrating first piece members, which arecomponents of core segments of the motor shown in FIG. 1;

FIG. 2(b) is a cross-sectional view taken along line 2 b—2 b in FIG.2(a);

FIG. 3(a) is a plan view illustrating second piece members, which arecomponents of core segments of the motor shown in FIG. 1;

FIG. 3(b) is a cross-sectional view taken along line 3 b—3 b in FIG.3(a);

FIG. 4(a) is a plan view illustrating a state where part of a statorcore of the motor shown in FIG. 1 is shown partially disassembled andenlarged;

FIG. 4(b) is a front view illustrating the stator core shown in FIG.4(a);

FIG. 4(c) is a perspective view illustrating the stator core shown inFIG. 4(a);

FIG. 5 is a perspective view illustrating an insulating member of themotor shown in FIG. 1;

FIG. 6 is a plan view illustrating a state where the insulating membershown in FIG. 5 is attached to the core segment;

FIG. 7 is a cross-sectional view illustrating holding portions of theinsulating member shown in FIG. 5;

FIG. 8 is a cross-sectional view taken along line 8—8 in FIG. 6;

FIG. 9 is a plan view illustrating a state where the core segments andinsulating members are rotated to broaden a space between adjacentteeth;

FIG. 10 is a plan view illustrating a state where a coil is wound aroundeach of the core segments and the insulating members shown in FIG. 9;

FIGS. 11 and 12 are plan views showing a complete round forming processfor a stator;

FIG. 13 is a perspective view illustrating a first insulating memberaccording to a second embodiment of the present invention;

FIG. 14 is a plan view illustrating the first insulating member shown inFIG. 13;

FIG. 15 is a perspective view illustrating a second insulating memberaccording to the second embodiment;

FIG. 16 is a plan view illustrating the second insulating member shownin FIG. 15;

FIG. 17 is a perspective view illustrating a first insulating memberaccording to a third embodiment of the present invention;

FIG. 18 is a plan view illustrating the first insulating member shown inFIG. 17;

FIG. 19 is a perspective view illustrating a second insulating memberaccording to the third embodiment;

FIG. 20 is a plan view illustrating the second insulating member shownin FIG. 19;

FIG. 21 is a plan view illustrating a state where the first and secondinsulating members are located at an allowable angle;

FIG. 22 is a cross-sectional view taken along line 22—22 in FIG. 21;

FIG. 23 is a plan view illustrating a state where the first and secondinsulating members, which are coupled to each other, are arranged in astraight line;

FIG. 24 is a plan view illustrating a state where the first and secondinsulating members, which are coupled to each other, are arranged in anannular form;

FIG. 25 is a plan view illustrating a manufacturing device for moldingthe insulating members shown in FIGS. 17 to 20;

FIG. 25A is an enlarged view of a portion surrounded by an oval in FIG.25;

FIG. 26 is a cross-sectional view taken along line 26—26 in FIG. 25A;

FIG. 27 is a cross-sectional view taken along line 27—27 in FIG. 25A;

FIG. 28 is an enlarged view corresponding to FIG. 25A showing an uppermold release process;

FIG. 29 is a cross-sectional view corresponding to FIG. 26 showing anupper mold release process;

FIG. 30 is a cross-sectional view corresponding to FIG. 27 showing anupper mold release process;

FIG. 31 is a cross-sectional view corresponding to FIG. 29 showing acoupling process;

FIG. 32 is a cross-sectional view corresponding to FIG. 30 showing acoupling process;

FIG. 33 is a perspective view illustrating an insulator according to afourth embodiment of the present invention;

FIG. 34 is a plan view illustrating the insulator shown in FIG. 33attached to the core segments; and

FIG. 35 is a plan view illustrating the insulator shown in FIG. 33attached to the core segments.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A first embodiment of the present invention will now be described withreference to FIGS. 1 to 12. As shown in FIG. 1, an electric rotatingmachine, which is a brushless motor in this embodiment, includes astator 1 and a rotor 2 (indicated with a dashed line in FIG. 1). Therotor 2 has magnets (not shown) located opposite to the stator 1. Thestator 1 is located in a substantially cylindrical housing 3 andsurrounds the rotor 2. The stator 1 includes a stator core 6, aninsulator 4, and coils 5.

The stator core 6 includes an annular portion 8 and teeth 7, whichextend from the annular portion 8 radially toward the axis of theannular portion 8. Each coil 5 is wound around one of the teeth 7. Inthe first embodiment, twelve teeth 7 are arranged at equal angularintervals of 30 degrees.

As shown in FIGS. 4(b) and 4(c), the stator core 6 is formed by coresegments (divided core members) 13 arranged in an annular form. Eachcore segment 13 is formed by alternately laminating first piece members11 (see FIGS. 2(a) and 2(b)) and second piece members 12 (see FIGS. 3(a)and 3(b)).

As shown in FIGS. 2(a) and 2(b), each first piece member 11 has anarcuate plate (divided annular portion) 11 a and a tooth plate 11 b,which extends from the circumferential middle portion of the arcuateplate 11 a. Each tooth plate 11 b extends in a direction substantiallyorthogonal to the corresponding arcuate plate 11 a. In other words, thetooth plate 11 b extends toward the axis of the arcuate plate 11 a. Aprojection 11 c is formed at the distal end of each tooth plate 11 b andextends in the circumferential direction. Two first recesses 11 d areformed on one of the surfaces of the tooth plate 11 b facing oppositedirections in the thickness direction (axial direction), and two firstprojections 11 e are formed on the other one of the surfaces. Each firstrecess 11 d and the corresponding first projection 11 e are formed atthe identical positions on different surfaces of the tooth plate 11 b.Two pairs of the first recess 11 d and the first projection 11 e arearranged next to each other in the longitudinal direction of each toothplate 11 b.

As shown in FIG. 2(a), an arcuate projection 11 f is formed at a firstend (left end) of each arcuate plate 11 a. The arcuate projection 11 fhas an arcuate projection shape when the arcuate plate 11 a is viewedfrom the axial direction. An arcuate recess 11 g is formed at a secondend (right end) of each arcuate plate 11 a. The arcuate recess 11 g hasan arcuate recess shape when the arcuate plate 11 a is viewed from theaxial direction. That is, the arcuate projections 11 f and the arcuaterecesses 11 g are formed such that when two first piece members 11 arearranged next to each other with the arcuate projection 11 f of one ofthe first piece members 11 abutting against the arcuate recess 11 g ofthe other first piece member 11 as shown in FIG. 2(a), the first piecemembers 11 are permitted to rotate relative to each other.

As shown in FIGS. 3(a) and 3(b), the second piece members 12 have ashape symmetric to the first piece members 11. That is, each secondpiece member 12 has an arcuate plate 12 a and a tooth plate 12 b, whichextends from the circumferential middle portion of the arcuate plate 12a toward the axis. A projection 12 c is formed at the distal end of eachtooth plate 12 b and extends in the circumferential direction. Twosecond recesses 12 d are formed on one of the surfaces of the toothplate 12 b facing opposite directions in the thickness direction (axialdirection), and two second projections 12 e are formed on the other oneof the surfaces. Each second recess 12 d and the corresponding secondprojection 12 e are formed at the identical position on differentsurfaces of the tooth plate 12 b. Two pairs of the second recess 12 dand the second projection 12 e are arranged next to each other in thelongitudinal direction of the tooth plate 12 b.

As shown in FIG. 3(a), an arcuate projection 12 f is formed at a secondend (right end) of each arcuate plate 12 a. The arcuate projection 12 fhas an arcuate projection shape when the arcuate plate 12 a is viewedfrom the axial direction. An arcuate recess 12 g is formed at a firstend (left end) of each arcuate plate 12 a. The arcuate recess 12 g hasan arcuate recess shape when the arcuate plate 12 a is viewed from theaxial direction. That is, the arcuate projections 12 f and the arcuaterecesses 12 g are formed such that when two second piece members 12 arearranged next to each other with the arcuate projection 12 f of one ofthe second piece members 12 abutting against the arcuate recess 12 g ofthe other second piece member 11 as shown in FIG. 3(a), the second piecemembers 12 are permitted to rotate relative to each other.

As shown in FIGS. 4(a) to 4(c), five first piece members 11 and fivesecond piece members 12 are alternately laminated to form a core segment13. The core segment 13 includes an arcuate portion (divided annularportion) 13 a, which is formed by alternately laminated arcuate plates11 a, 12 a, and the tooth 7, which is formed by alternately laminatedtooth plates 11 b, 12 b. The first and second piece members 11, 12 aresecured to one another by press-fitting the first projections 11 e inthe second recesses 12 d and press-fitting the second projections 12 ein the first recesses 11 d. At the first end of the arcuate portion 13 aof the core segment 13, the arcuate projections 11 f and the arcuaterecesses 12 g are arranged alternately. At the second end of the arcuateportion 13 a of the core segment 13, the arcuate projections 12 f andthe arcuate recesses 11 g are arranged alternately (see FIG. 4(b)). Whenseveral core segments 13 are arranged next to one another in an annularform, the annular portion 8, which includes arcuate portions 13 a, isformed and the teeth 7 are arranged radially (see FIG. 1). In thisstate, the recesses and projections on each circumferential end of thearcuate portion 13 a of each core segment fit with the recesses andprojections on the corresponding circumferential end of the arcuateportion 13 a of the adjacent core segment 13. That is, the arcuateprojections 11 f, 12 f overlap one another in the axial direction.

The insulator 4 includes insulating members 21 as shown in FIGS. 5 and6. Each insulating member 21 corresponds to one of the core segments 13.The insulating members 21 are formed of insulative and flexible resinmaterial. Each insulating member 21 includes an arcuate cover 21 a, aninner circumferential cover 21 b, a flat cover 21 c, and a pair of sidecovers 21 d. The arcuate cover 21 a covers one of the surfaces of thecorresponding arcuate portion 13 a that faces different directions fromeach other in the axial direction. The inner circumferential cover 21 bcovers the inner circumferential surface of the corresponding arcuateportion 13 a. The flat cover 21 c covers the surface of thecorresponding tooth 7, which is connected to the surface of the arcuateportion 13 a covered by the arcuate cover 21 a. The side covers 21 dcover the side surfaces of the corresponding tooth 7. The innercircumferential cover 21 b has an outer restricting wall 21 e forpreventing the coil 5 wound around the corresponding tooth 7 fromprotruding radially outward. The flat cover 21 c has an insiderestricting wall 21 f at the end that corresponds to the distal end ofthe corresponding tooth 7 (lower end as viewed in FIG. 6). The insiderestricting wall 21 f prevents the coil 5 wound around the correspondingtooth 7 from protruding radially inward.

The side covers 21 d extend from the flat cover 21 c and aresubstantially perpendicular to the flat cover 21 c. Each side cover 21 dhas a holding portion 21 g as shown in FIG. 7. When each insulatingmember 21 is not attached to the corresponding tooth 7, the distancebetween the side covers 21 d at the holding portions 21 g is narrowerthan the distance between the side surfaces of the tooth 7. Therefore,when each insulating member 21 is attached to the corresponding tooth 7,the tooth 7 is held by the side covers 21 d as shown in FIG. 7. In thefirst embodiment, the holding portions 21 g are formed by flexing theentire side covers 21 d inward. The distance between the distal ends(lower end as viewed in FIG. 7) of the side covers 21 d is slightlygreater than the distance between the side surfaces of the correspondingtooth 7. Therefore, each insulating member 21 is easily attached to thecorresponding tooth 7. In FIG. 7, the degree of curvature is exaggeratedto facilitate understanding the shape of the holding portions 21 g.

Coupling portions 22 (see FIG. 6) are formed at portions of theinsulator 4 that correspond to the circumferential ends of each arcuateportion 13 a, that is, at the circumferential ends of each arcuate cover21 a. Each coupling portion 22 rotatably couples the adjacent coresegments 13 with each other.

More specifically, a substantially circular upper coupling portion 22 ais formed at a first circumferential end (left end as viewed in FIG. 6)of each arcuate cover 21 a. As shown in FIG. 5, the upper couplingportion 22 a is formed by removing the lower half of the thickness ofthe first circumferential end of each arcuate cover 21 a in asubstantially circular shape. A substantially circular lower couplingportion 22 b is formed at a second circumferential end (right end asviewed in FIG. 6) of each arcuate cover 21 a. As shown in FIG. 5, thelower coupling portion 22 b is formed by removing the upper half of thethickness of the second circumferential end of each arcuate cover 21 ain a substantially circular shape. A coupling bore 22 c extends axiallythrough each lower coupling portion 22 b. A coupling projection 22 d isformed on each upper coupling portion 22 a to be inserted in thecoupling bore 22 c of the adjacent insulating member 21 (see FIG. 8).

Each coupling projection 22 d can be loosely fitted to the correspondingcoupling bore 22 c. The coupling bores 22 c and the coupling projections22 d are non-circular as viewed from the axial direction. As shown inFIG. 6, when the core segments 13 are arranged in a straight line, aspace is formed between the inner circumferential surface of eachcoupling bore 22 c and the outer circumferential surface of thecorresponding coupling projection 22 d along the entire circumference.When the core segments 13 are rotated until the core segments 13 arearranged in an annular form as shown in FIG. 1, the smallest portion ofthe space between the inner circumferential surface of each couplingbore 22 c and the outer circumferential surface of the correspondingcoupling projection 22 d is reduced to zero. In the state shown in FIG.1, the inner circumferential surface of each coupling bore 22 c contactsthe outer circumferential surface of the corresponding couplingprojection 22 d at two positions on a line orthogonal to a relativerotational axis of the adjacent insulating members 21. In the firstembodiment, the coupling bores 22 c and the coupling projections 22 dhave a substantially oval shape as viewed from the axial direction asshown in FIG. 6. The major axis and the minor axis of each couplingprojection 22 d are smaller than those of the corresponding couplingbore 22 c.

A hook 22 e is formed at the distal end (lower end as viewed in FIG. 8)of each coupling projection 22 d to prevent the coupling projection 22 dfrom falling out of the corresponding coupling bore 22 c. The hook 22 eextends radially outward from the coupling projection 22 d. The hook 22e has a guide surface 22 i, which inclines with respect to a plane thatis perpendicular to the axis of the coupling projection 22 d.

An axial bore 22 f extends through each coupling projection 22 d. Thecoupling projections 22 d are therefore cylindrical. The axial bores 22f make the coupling projections 22 d flexible.

In the first embodiment, each coupling bore 22 c and the correspondingcoupling projection 22 d, which are fitted to each other, form thecoupling portion 22. That is, each insulating member 21, which is formedas described above, is attached to one of the core segments 13 in whichthe arcuate projections 11 f, 12 f overlap one another in the axialdirection. Accordingly, the core segments 13 that are adjacent to eachvia each coupling portion 22 are rotatably coupled to each other. Wheneach insulating member 21 is attached to the corresponding core segment13, the axis of the coupling bore 22 c and the coupling projection 22 dsubstantially matches the axis of the arcuate projections 11 f, 12 f andthe arcuate recesses 11 g, 12 g. The adjacent core segments 13 rotaterelative to each other about the matched axis. Since each couplingprojection 22 d is loosely fitted to the corresponding coupling bore 22c, the coupling portions 22 are flexible. In other words, the relativeposition of the adjacent core segments 13 as viewed from the axialdirection can be slightly changed as required. In the first embodiment,a pair of insulating members 21 is attached to one core segment 13 insuch a way the insulating members 21 face each other in the axialdirection of the core segment 13.

Each coil 5 is wound around the corresponding tooth 7 to which the pairof insulating members 21 is attached while the space between the distalends of the adjacent teeth 7 is broadened as shown in FIGS. 9 and 10.The coil 5 is wound around the flat cover 21 c and the side covers 21 dof each insulating member 21. The core segments 13 are then fixed suchthat the arcuate portions 13 a form the annular portion 8 and the teeth7 are arranged in a radial pattern. As a result, the stator 1 is formed.

A method for manufacturing the stator 1, which is formed as describedabove, will now be described.

In a first punching process, the first piece members 11 are punched fromplate material, which is not shown.

In a second punching process, the second piece members 12 are punchedfrom plate material, which is not shown.

In a laminating process performed after the first and second punchingprocesses, the first piece members 11 and the second piece members 12are laminated alternately to form the core segment 13. Then, theseparate core segments 13 are moved in the longitudinal direction of thearcuate portions 13 a as shown by arrows A in FIG. 4(a). Accordingly,the arcuate projections 11 f, 12 f of the adjacent core segments 13overlap one another in the axial direction. That is, the adjacent coresegments 13 are fitted to each other (see FIGS. 4(a) to 4(c)).

In an attaching and coupling process that follows the laminatingprocess, the pair of insulators 4 is attached to the core segments 13from both sides of the core segments 13 in the axial direction while thearcuate projections 11 f, 12 f of the adjacent core segments 13 overlapone another in the axial direction. This couples the core segments 13 toone another. More specifically, the attaching and coupling process ofthe first embodiment includes an insulator coupling process in whichinsulating members 21 are coupled to one another. In the insulatorcoupling process, the insulating members 21 (twelve insulating members21 in this embodiment) are coupled to one another by inserting eachcoupling projection 22 d to the corresponding coupling bore 22 c.Accordingly, the insulator 4, which is formed by the insulating members21, is obtained. As shown in FIG. 6, the insulating members 21 that arecoupled to one another are attached to the core segments 13 by coveringthe core segments 13 from the axial direction while the arcuateprojections 11 f, 12 f of the adjacent core segments 13 overlap oneanother. At this time, the insulating members 21 are attached to thecore segments 13 such that each pair of holding portions 21 g holds thecorresponding tooth 7 by only moving the insulating members 21 in theaxial direction of the core segments 13. In FIG. 6, only two coresegments 13 and two insulating members 21 are shown.

In a winding process, which follows the attaching and coupling process,each coil 5 is wound around one of the teeth 7 via the flat cover 21 cand the side covers 21 d of each of the pair of insulating members 21while the space between the distal ends of the adjacent teeth 7 isbroadened as shown in FIGS. 9 and 10.

In a complete round forming process, which follows the winding process,the core segments 13, which are coupled to one another, are rolled up asshown in FIG. 11. Pressure is then applied to the core segments 13 fromthe circumference of the core segments 13 to form a complete round. Morespecifically, in the complete round forming process, the core segments13, which are coupled to one another, are rolled up by a core metal 31having a complete round outer circumference. Each core segment 13 isthen pressed from the radially outward direction as shown in FIG. 12(see the arrows shown in broken lines in FIG. 12). This increases thecircularity of the stator 1.

In a welding process, which follows the complete round forming process,the circumferential ends of the arcuate portions 13 a of the adjacentcore segments 13, or the arcuate projections 11 f, 12 f, which overlapone another in the axial direction, are welded. In the first embodiment,the number of core segments 13 is twelve. Therefore, the number ofwelding portions is twelve. For example, laser welding is performed. Asa result, the core segments are fixed to one another and the stator 1 iscompleted.

The first embodiment of the present invention provides the followingadvantages.

(1) When the core segments 13 are arranged in an annular form, thearcuate projections 11 f, 12 f of the adjacent core segments 13 overlapone another. Therefore, a linear space does not extend in the axialdirection between the adjacent core segments 13. This reduces themagnetic resistance between the adjacent arcuate portions 13 a and formsa reliable magnetic circuit. This also prevents the core segments 13from being displaced in the axial direction.

Furthermore, the arcuate plate 11 a of each first piece member 11 hasthe arcuate projection 11 f and the arcuate recess 11 g, and the arcuateplate 12 a of each second piece member 12 has the arcuate projection 12f and the arcuate recess 12 g. Therefore, the adjacent core segments 13are permitted to rotate relative to each other with the arcuateprojections 11 f, 12 f of the adjacent core segments 13 overlapping oneanother in the axial direction. The adjacent core segments 13 arerotatably coupled to each other with the corresponding coupling portion22 of the insulator 4 easily with the arcuate projections 11 f, 12 foverlapping one another. Therefore, the adjacent core segments 13 can berotated relative to each other while being kept coupled to each other tobroaden the space between the distal ends of the adjacent teeth 7. As aresult, each coil 5 is easily wound around the corresponding tooth 7without interference from the adjacent tooth 7. Furthermore, the coresegments 13 are easily arranged in an annular form by only rotating thecore segments 13, to which the coils 5 are wound, relative to oneanother. With this structure, a coupling portion need not be formed oneach core segment 13 to couple the core segments 13 with one another.Also, pins such as those used in the prior art need not be provided tocouple the adjacent core segments 13. This contributes to reducing thenumber of parts and the types of parts.

(2) Each coupling projection 22 d is loosely fitted to the correspondingcoupling bore 22 c. The insulating members 21 are formed of flexibleresin material. Therefore, the coupling portions 22 are flexible andpermit slight changes in the relative position between the adjacent coresegments 13. Thus, as compared to the prior art, the circularity of theannular portion 8 is improved. More specifically, in the prior art inwhich pins are used, the machining accuracy of the hard piece members(particularly, the machining accuracy of the circumferential ends ofeach piece member and the pin holes) must be increased to obtain highcircularity. In contrast, when the coupling portions 22 of the insulator4 are flexible as in the first embodiment, the coupled core segments 13can be reliably wound around the core metal 31 to closely contact thecore metal 31 even if the accuracy of the insulator 4 and the piecemembers 11, 12 is relatively low. In this state, the circumferentialends of the adjacent arcuate portions 13 a are fixed to each other bywelding. As a result, an annular portion 8 having high circularity iseasily obtained. Since the insulating members 21 are formed of flexibleresin material, the insulating members 21 can deform to compensate forslight errors. Thus, the insulating members 21 need not be formed withhigh accuracy.

(3) The arcuate cover 21 a of each insulating member 21 has the couplingprojection 22 d on the first end of the arcuate cover 21 a and thecoupling bore 22 c on the second end of the arcuate cover 21 a. Thecoupling portion 22 is easily formed by inserting the couplingprojection 22 d of one of the adjacent insulating members 21 into thecoupling bore 22 c of the other one of the adjacent insulating members21. When forming each core segment 13, the lamination of the first andsecond piece members 11, 12, the coupling of the insulating members 21,and the attachment of the insulating members 21 to the core segments 13are all performed wile moving the components in the same direction. Thisfacilitates manufacturing processes for the stator core 6 and permitsautomation of the manufacturing while preventing the manufactured devicefrom being complicated and enlarged. Furthermore, in the firstembodiment, only one type of insulating member 21 needs to be prepared.This reduces the manufacturing cost.

(4) As shown in FIG. 6, the coupling bores 22 c and the couplingprojections 22 d have a substantially oval shape as viewed from theaxial direction. When the core segments 13 are arranged in a straightline as shown in FIG. 6, a space is formed between the innercircumferential surface of each coupling bore 22 c and the outercircumferential surface of the corresponding coupling projection 22 dalong the entire circumference. Therefore, the insulating members 21 areeasily coupled to each other without determining the position with highaccuracy. When the core segments 13 are arranged in an annular form asshown in FIG. 1, the inner circumferential surface of each coupling bore22 c contacts the outer circumferential surface of the correspondingcoupling projection 22 d at two positions. Therefore, the core segments13 that are coupled to each other are prevented from being displacedrelative to each other. This suppresses noise caused by suchdisplacement. Furthermore, in a state where the distance between theteeth 7 of the adjacent core segments 13 is broadened as shown in FIG.9, the inner circumferential surface of each coupling bore 22 c contactsthe outer circumferential surface of the corresponding couplingprojection 22 d at two positions. Therefore, when winding each coil 5 tothe corresponding tooth 7, the adjacent core segments 13 that arecoupled to each other are prevented from being displaced from eachother. This permits an operator to smoothly wind each coil 5 on thecorresponding tooth 7.

(5) The hook 22 e having the guide surface 22 i is formed at the distalend (lower end as viewed in FIG. 8) of each coupling projection 22 d.The hook 22 e prevents each coupling projection 22 d from falling out ofthe corresponding coupling bore 22 c. The guide surface 22 i of the hook22 e facilitates inserting each coupling projection 22 d into thecorresponding coupling bore 22 c.

(6) The axial bore 22 f is formed in each coupling projection 22 d.Therefore, when inserting each coupling projection 22 d into thecorresponding coupling bore 22 c, the coupling projection 22 d easilyflexes thereby facilitating inserting the coupling projection 22 d intothe coupling bore 22 c.

(7) When each insulating member 21 is attached to the correspondingtooth 7, the holding portions 21 g formed on the pair of side covers 21d of the insulating member 21 holds the tooth 7. Therefore, eachinsulating member 21 is easily kept attached to the corresponding coresegment 13.

(8) The pair of insulators 4 is attached to the group of successive coresegments 13 from the axial direction of the group of core segments 13.Therefore, the adjacent core segments 13 are reliably maintained in acoupled state.

(9) The core segments 13 are easily coupled to one another only byattaching the insulators 4, each of which is formed of coupledinsulating members 21, to the group of core segments 13 in which arcuateprojections 11 f, 12 f overlap one another. In this case, severalinsulating members 21 are attached to several core segments 13 at once.This facilitates the attaching process and reduces the time and costspent for the attaching process.

A second embodiment of the present invention will now be described withreference to FIGS. 13 to 16.

The insulator 4 shown in FIG. 5 is formed by several identicalinsulating members 21, which are coupled to one another. In the secondembodiment, the insulator 4 is formed by alternately arranging two typesof insulating members as shown in FIGS. 13 to 16. That is, the insulator4 is formed by first insulating members 33 (see FIG. 13) and secondinsulating members 34 (see FIG. 15), which are coupled to one another.

More specifically, the first and second insulating members 33, 34 areformed of insulative resin material. As the insulating member 21 shownin FIG. 5, each insulating member 33 or 34 includes an arcuate cover 33a or 45 a, an inner circumferential cover 33 b or 34 b, a flat cover 33c or 34 c, and a pair of side covers 33 d or 34 d. Each arcuate cover 33a or 34 a has a restricting wall for preventing the coil 5 wound aroundthe corresponding tooth 7 from protruding radially outward. Therestricting wall has a pair of grooves 33 e or 34 e. The ends of eachcoil 5 can be secured to the grooves 33 e or 34 e. The flat cover 33 cor 34 c has an inner restricting wall 33 f or 34 f at the endcorresponding to the distal end of the tooth 7 (the lower end as viewedin FIGS. 14 and 16) for preventing the coil 5 wound around thecorresponding tooth 7 from protruding radially inward.

Coupling portions are formed at portions of the insulator 4 thatcorrespond to the circumferential ends of the arcuate portion 13 a ofeach core segment 13. That is, the coupling portions are formed at thecircumferential ends of the arcuate covers 33 a, 34 a to rotatablycouple the adjacent core segments 13.

More specifically, as shown in FIGS. 13 and 14, coupling bores 33 g areformed on the circumferential ends of the arcuate cover 33 a of eachfirst insulating member 33 and extend in the axial direction. Thecoupling bores 33 g have circular shapes as viewed from the axialdirection. As shown in FIGS. 15 and 16, coupling projections 34 g areformed on the circumferential ends of the arcuate covers 34 a of eachsecond insulating member 34. The coupling projections 34 g extend in theaxial direction and can be inserted into the coupling bores 33 g. Thecoupling projections 34 g have circular shape as viewed from the axialdirection. The coupling bores 33 g and the coupling projections 34 g,which are coupled to each other, form the coupling portions in thesecond embodiment. The insulator 4, which is formed by alternatelyarranging the first and second insulating members 33, 34, is attached tothe core segments 13 (see FIG. 4(c)) in which arcuate projections 11 f,12 f overlap one another in the axial direction. As a result, the coresegments 13 that are adjacent to each other via each coupling portionare rotatably coupled to each other by the engagement of each couplingbore 33 g with the corresponding coupling projection 34 g. When theinsulating members 33, 34 are attached to the core segments 13, the axesof the coupling bores 33 g and the coupling projections 34 gsubstantially match the axes of the arcuate projections 11 f, 12 f andthe arcuate recesses 11 g, 12 g. Two insulators 4, each of which isformed by coupling the first and second insulating members 33, 34, areprepared and attached to the group of core segments 13 to face eachother.

In the second embodiment, one insulator 4 is formed by coupling thetotal of twelve alternately arranged first and second insulating members33, 34 to one another by inserting each coupling projection 34 g intothe corresponding coupling bore 33 g.

In the second embodiment, the first insulating member 33 having the pairof coupling bores 33 g and the second insulating member 34 having thepair of coupling projections 34 g are prepared. Therefore, theinsulating members 33, 34 can be assembled at once by, for example,arranging the first insulating members 33 and the second insulatingmembers 34 on different planes and moving one of the groups ofinsulating members toward the other one of the groups of insulatingmembers.

A third embodiment of the present invention will now be described withreference to FIGS. 17 to 32.

In the third embodiment, the first and second insulating members 33, 34of the second embodiment illustrated in FIGS. 13 to 16 are slightlymodified. As shown in FIGS. 17 and 18, a notch 33 h is formed in eachcoupling bore 33 g of the first insulating member 33 according to thethird embodiment. The notch 33 h extends in the radial direction. Thepair of notches 33 h of each first insulating member 33 extends indirections to separate from each other toward the lower side, that is,toward the inner restricting wall 33 f as shown in FIG. 18.

As shown in FIGS. 19 and 20, a hook 34 h is formed at the distal end ofeach coupling projection 34 g of the second insulating member 34. Theshape of the hooks 34 h matches the shape of the notches 33 h. The hooks34 h permit the coupling projections 34 g to be inserted into thecoupling bores 33 g when the first insulating member 33 and the secondinsulating member 34 are arranged at a predetermined angle (allowableangle). However, when the first insulating member 33 and the secondinsulating member 34 are arranged at an angle other than the allowableangle, the hooks 34 h prevent the coupling projections 34 g from beinginserted into or removed from the coupling bores 33 g. That is, thehooks 34 h match the notches 33 h only when the first insulating member33 and the second insulating member 34 are arranged at the allowableangle. As shown in FIG. 20, the pair of hooks 34 h of the secondinsulating member 34 extends in directions to separate them from eachother toward the lower side, that is, toward the inner restricting wall34 f.

The allowable angle is set to an angle formed when the total of twelvefirst and second insulating members 33, 34 are arranged in an annularform such that the portions that cover the teeth 7 face radially outwardas shown in FIG. 21. When the first and second insulating members 33, 34are arranged at the allowable angle, each hook 34 h matches thecorresponding notch 33 h as shown in FIG. 22, and permits each couplingprojection 34 g to be inserted into the corresponding coupling bore 33g. Therefore, when the first and second insulating members 33, 34 arearranged in a state as shown in FIG. 21, each coupling projection 34 gis inserted into the corresponding coupling bore 33 g so that the firstand second insulating members 33, 34 are rotatably coupled to eachother. Among the total of twelve first and second insulating members 33,34, which are coupled to one another, one of the first insulatingmembers 33 only has one coupling bore 33 g and one of the secondinsulating members 34 has only one coupling projection 34 g. The firstinsulating member 33 that has only one coupling bore 33 g and the secondinsulating member 34 that has only one coupling projection 34 g arelocated at the ends of the series of coupled insulating members.

FIG. 23 shows the total of twelve first and second insulating members33, 34 that are coupled to one another in a straight line. In the thirdembodiment, each coil 5 is wound around the corresponding insulatingmember 33 or 34, which surrounds one of the teeth 7, when the first andsecond insulating members 33, 34 are arranged as shown in FIG. 23. Atthis time, since the angle between each first insulating member 33 andthe adjacent second insulating member 34 is not the allowable angle,each hook 34 h does not match the corresponding notch 33 h (see enlargedview in FIG. 23). Therefore, each coupling projection 34 g is preventedfrom falling out of the corresponding coupling bore 33 g.

FIG. 24 shows a state where the total of twelve first and secondinsulating members 33, 34 are arranged in an annular form such thatportions covering the teeth 7 face radially inward. In this state, theinsulator 4 formed by the total of twelve first and second insulatingmembers 33, 34 has a shape corresponding to the annular stator core 6.At this time, since the angle between each first insulating member 33and the adjacent second insulating member 34 is not the allowable angle,each hook 34 h does not match the corresponding notch 33 h (see enlargedview in FIG. 24). Therefore, each coupling projection 34 g is preventedfrom falling out of the corresponding coupling bore 33 g.

A method and device for manufacturing the stator 1 will now bedescribed.

As shown in FIGS. 25 to 27, the manufacturing device (molding equipment)includes a lower mold 131, an upper mold 132, a plurality of slide cores133, 134, and a plurality of push-out members 135. FIG. 25 is a planview illustrating a state where the upper mold 132 is separated from thelower mold 131 after the first and second insulating members 33, 34 aremolded. Therefore, the upper mold 132 is not shown in FIG. 25. FIGS. 26and 27 show the upper mold 132. The molding equipment molds the firstand second insulating members 33, 34 such that the first insulatingmembers 33 are axially displaced from the second insulating members 34and the angle between the adjacent first and second insulating members33, 34 is the allowable angle (see FIG. 9).

The lower mold 131 defines a lower mold cavity having a shape thatcorresponds to the lower part of the first and second insulating members23, 24, that is, mainly a part lower than the under surface of the flatcover 33 c, 34 c. The upper mold 132 defines an upper mold cavity havinga shape that corresponds to the upper part of the first and secondinsulating members 33, 34, that is, mainly the part higher than theunder surface of the flat cover 33 c, 34 c. The lower mold 131 and theupper mold 132 mold the total of twelve first and second insulatingmembers 33, 34 (six each) such that the first and second insulatingmembers 33, 34 are in the state shown in FIG. 21 as viewed from the top.As shown in FIG. 26, in the lower mold 131 and the upper mold 132, moldcavity portions corresponding to the first insulating members 33 areaxially displaced from mold cavity portions corresponding to the secondinsulating members 34. Therefore, when the first and second insulatingmembers 33, 34 are molded to be arranged alternately, the firstinsulating members 33 are located axially upward and the secondinsulating members 34 are located axially downward. As shown in FIG. 25,the lower mold 131 and the upper mold 132 define resin injectionpassages 136, which extend radially outward from the center of the lowerand upper molds 131, 132 to the mold cavities.

As shown in FIGS. 25A and 27, pairs of inner and outer slide cores 133and 134 are formed at positions corresponding to the coupling bores 33 gand the coupling projections 34 g and extend in the radial direction.The inner and outer slide cores 133, 134 are movable in the radialdirection and define cavities for molding the coupling projections 34 g.As shown in FIGS. 26, 27, the push-out members 135 are inserted in thelower mold 131 such that the push-out members 135 can move up and downat positions corresponding to the coupling bores 33 g and the couplingprojections 34 g.

In a molding process, molten resin is injected into the mold cavities inthe molding equipment through the resin injection passages 136. As aresult, the total of twelve first and second insulating members 33, 34(six each) are molded in the mold cavities. At this time, the firstinsulating members 33 are axially displaced from the second insulatingmembers 34 (see FIG. 26) and the angle between the adjacent first andsecond insulating members 33, 34 is the allowable angle (see FIG. 25A).

After the molding process, that is, after the resin is hardened, a moldrelease process is performed. The mold release process includes an uppermold release process, a coupling process, and a lower mold releaseprocess.

In the upper mold release process, as shown in FIGS. 28 to 30, the uppermold 132 is moved upward and the inner and outer slide cores 133, 134are moved in the radial direction such that the inner and outer slidecores 133, 134 separate from each other. FIG. 28 shows a change from thestate shown in FIG. 25A, FIG. 29 shows a change from the state shown inFIG. 26, and FIG. 30 shows a change from the state shown in FIG. 27.

In the subsequent coupling process, either of the first insulatingmembers 33 or the second insulating members 34 are moved in the axialdirection while the first and second insulating members 33, 34 are stilllocated at the allowable angle. Accordingly, each coupling projection 34g is inserted into the corresponding coupling bore 33 g thereby couplingthe first and second insulating members 33, 34 to one another. Morespecifically, in the coupling process, as shown in FIGS. 31 and 32, eachpush-out member 135 moves to a first push-out position to lift thecorresponding second insulating member 34 upward. At this time, eachsecond insulating member 34 slides along a corresponding one of thecontact surfaces 137 (see FIG. 31) formed in the lower mold 131. Sincethe adjacent first and second insulating members 33, 34 define theallowable angle, the hooks 34 h match the notches 33 h. Therefore, eachcoupling projection 34 g is inserted into the corresponding couplingbore 33 g thereby rotatably coupling the adjacent first and secondinsulating members 33, 34. FIG. 31 shows a change from the state shownin FIG. 29 and FIG. 32 shows a change from the state shown in FIG. 30.

In the following lower mold release process, each push-out member 135 isfurther moved upward to a second push-out position to lift thecorresponding first insulating member 33 with the corresponding secondinsulating member 34 (not shown). As a result, the first and secondinsulating members 33, 34 are removed from the mold.

In a serialization process, which follows the mold release process, thefirst and second insulating members 33, 34 are arranged in a straightline as shown in FIG. 23. In this state, the hooks 34 h do not match thenotches 33 h (see the enlarged view in FIG. 23). Therefore, eachcoupling projection 34 g can be removed from the corresponding couplingbore 33 g.

In an attachment process, the group of first and second insulatingmembers 33, 34, or the insulator 4, is attached to the group of coresegments 13 arranged in a straight line as shown in FIGS. 4(a) to 4(c).This rotatably couples the adjacent core segments 13 to each other. Theattaching process is the same as that explained in the first embodimentillustrated in FIGS. 1 to 12. Manufacture of the core segments 13 isalso the same as that explained in the first embodiment illustrated inFIGS. 1 to 12.

The first piece members 11 are punched from plate material to bearranged in a straight line, and the second piece members 12 are punchedfrom plate material to be arranged in a straight line. The first piecemembers 11 arranged in a straight line and the second piece members 12arranged in a straight line may be laminated alternately to form thegroup of core segments 13 as shown in FIGS. 4(a) to 4(c). Thisfacilitates the series of processes from the punching of the piecemembers 11, 12 to the attachment of the insulators 4. The piece members11, 12 are efficiently punched from plate material reducing the amountof plate remaining after punching (waste material). Accordingly, wastematerial is reduced.

In a coiling process, each coil 5 is wound about one of the coresegments 13 to which the insulators 4 are attached. At this time, thecore segments 13 are still arranged in a straight line, that is, theteeth 7 are arranged parallel to one another (see FIGS. 4(a) to 4(c)).

The next complete round forming process is the same as that explainedwith reference to FIGS. 11 and 12. The stator 1 is completed after thecomplete round forming process is performed.

The third embodiment provides the following advantages.

The first and second insulating members 33, 34 are permitted to becoupled to one another and separated from one another only when thefirst and second insulating members 33, 34 are arranged at thepredetermined allowable angle. Therefore, after coupling the first andsecond insulating members 33, 34 at the allowable angle, the first andsecond insulating members 33, 34 are maintained in the coupled state byonly arranging the first and second insulating members 33, 34 at anangle other than the allowable angle. This facilitates coupling of thefirst and second insulating members 33, 34 and prevents the first andsecond insulating members 33, 34 from being accidentally separated fromone another. For example, when winding each coil 5, the first and secondinsulating members 33, 34 are maintained at an angle where each couplingprojection 34 g cannot be removed from the corresponding coupling bore33 g. Therefore, when winding each coil 5, the first and secondinsulating members 33, 34, or the core segments 13, are reliablymaintained as being coupled to one another.

The first and second insulating members 33, 34 are molded such that thefirst and second insulating members 33, 34 are displaced in the axialdirection and are arranged at the allowable angle. Moving either of thefirst or second insulating members 33, 34 that are maintained at theallowable angle in the axial direction inserts each coupling projection34 g into the corresponding coupling bore 33 g thereby coupling thefirst and second insulating members 33, 34 to one another. In this case,the series of processes from molding to coupling the first and secondinsulating members 33, 34 is performed without changing the anglebetween the first and second insulating members 33, 34. Therefore, thefirst and second insulating members 33, 34 that are coupled to oneanother, or the insulators 4, are easily obtained.

The push-out members 135 of the molding equipment lift the molded secondinsulating members 34 so that each coupling projection 34 g is insertedinto the corresponding coupling bore 33 g. This further facilitatescoupling the first and second insulating members 33, 34.

When being raised by the push-out members 135, each second insulatingmember 34 slides along the corresponding contact surface 137 of thelower mold 131. This prevents the second insulating members 34 frombeing displaced while being raised and reliably inserts each couplingprojection 34 g into the corresponding coupling bore 33 g.

The above mentioned molding process executed by the molding equipment isalso applicable to the second embodiment illustrated in FIGS. 13 to 16.

A fourth embodiment of the present invention will now be described withreference to FIGS. 33 to 35.

In the first to third embodiments, the insulator 4 is formed by couplingseparate insulating members. However, the insulator 41 of the fourthembodiment is an integrally molded part as shown in FIGS. 33 to 35. Theinsulator 41 includes insulating members 42, the number of which istwelve. Each insulating member 42 corresponds to one of the coresegments 13. The insulator 41 also includes thin and flexible couplingportions 43, each of which couples the adjacent insulating members 42.The insulating member 42 does not have the arcuate cover 21 a of theinsulating member 21 shown in FIG. 5. Each coupling portion 43 couplesthe outer restricting walls 21 e of the adjacent insulating members 42with each other. The insulator 41 shown in FIG. 33 easily couples theadjacent core segments 13 to rotate relative to each other with thecoupling portions 43 as shown in FIGS. 34 and 35. Furthermore, since theinsulator 41 is an integrally molded part, which includes the insulatingmembers 42 and the coupling portions 43, the insulator 41 has a simpleshape and prevents the number of parts from increasing.

The embodiments of the present invention may be modified as follows.

In the first to third embodiments, the structure of each couplingportion between the adjacent insulating members may be modified asrequired. For example, in the first embodiment illustrated in FIGS. 1 to12, the coupling bores 22 c and the coupling projections 22 d need nothave an oval cross-section but may have a circular cross-section as inthe second embodiment illustrated in FIGS. 13 to 16. In contrast, in thesecond embodiment illustrated in FIGS. 13 to 16, the coupling bores 33 gand coupling projections 34 g need not have a circular cross-section butmay have an oval cross-section as in the first embodiment illustrated inFIGS. 1 to 12. Alternatively, in the first to third embodiments, thecoupling bores need not be through holes as long as the coupling boresare recesses that can receive the coupling projections. That is, eachcoupling portion between the first insulating member and the secondinsulating member need only be formed by a coupling projection and acoupling opening that can receive the coupling projection.

The structure of the coupling portions according to the third embodimentillustrated in FIGS. 17 to 32 may be applied to the first embodiment ofFIGS. 1 to 12. That is, in the first embodiment in which the insulator 4is formed by the same insulating members 21, a circular coupling holehaving a notch may be formed in one of the circumferential ends of eachinsulating member 21 and a circular coupling projection having a hookmay be formed on the other one of the circumferential ends of theinsulating member 21.

The hook 22 e of each coupling projection 22 d may be omitted. Insteadof forming the axial bore 22 f in each coupling projection 22 d, thecoupling projections 22 d may be solid bodies.

The pair of holding portions 21 g shown in FIG. 7 is formed by flexingthe entire side covers 21 d inward. Instead, for example, the sidecovers 21 d may be flat and projections that function as holdingportions may be formed on the inner surfaces of the side covers 21 d.Alternatively, the holding portions 21 g may be omitted. That is, theside covers 21 d may simply be flat plates.

In the third embodiment illustrated in FIGS. 17 to 32, the coils 5 maybe wound around the insulating members 33, 34 in a state as shown inFIG. 21 and the allowable angle may be set to the angle obtained whenthe insulating members 33, 34 are arranged as shown in FIG. 23. In thiscase, the orientation of at least either the notches 33 h or the hooks34 h needs to be modified.

In the third embodiment illustrated in FIGS. 17 to 32, the push-outmembers 135 lift the second insulating members 34 to insert eachcoupling projection 34 g into the corresponding coupling bore 33 g.However, the inserting process for each coupling projection 34 g intothe corresponding coupling bore 33 g is not limited to this. Instead,the first insulating members 33 may be moved, or both the first andsecond insulating members 33, 34 may be moved at the same time. That is,at least one of the first and second insulating members 33, 34 need tobe moved in the axial direction.

In the third embodiment illustrated in FIGS. 17 to 32, the push-outmembers 135, each of which corresponds to and is located below one ofthe coupling projections 34 g, move the first and second insulatingmembers 33, 34 upward. However, the first and second insulating members33, 34 may be moved upward with a mechanism different from the push-outmembers 135. The push-out members 135 may also be located at positionsdisplaced from the coupling projections 34 g. Furthermore, push-outmembers corresponding to the first insulating members 33 and push-outmembers corresponding to the second insulating members 34 may beprovided separately.

In the illustrated embodiments, the arcuate projections 11 f, 12 f atthe circumferential ends of the adjacent core segments 13 overlap oneanother in the axial direction. However, the circumferential ends of theadjacent core segments 13 need not overlap one another in the axialdirection. The adjacent core segments 13 may be rotatably coupled toeach other with, for example, a pin. Instead of forming each coresegment by laminating piece members, each core segment may be formed asan integral part by sintering magnetic powder.

The number of the core segments 13 forming the stator core 6 need not betwelve. The number of the insulating members forming the insulator neednot be twelve.

Therefore, the present examples and embodiments are to be considered asillustrative and not restrictive and the invention is not to be limitedto the details given herein, but may be modified within the scope andequivalence of the appended claims.

1. An insulator for attachment to a core having an annular portion and aplurality of teeth, which teeth extend radially from the annularportion, the core being divided into a plurality of core segments in thecircumferential direction, with adjacent core segments being permittedto rotate relative to each other, wherein the insulator is forinsulating a coil wound around each tooth from the core, the insulatorcomprising: a plurality of coupling portions, wherein each couplingportion couples the adjacent core segments so as to be rotatablerelative to each other.
 2. The insulator according to claim 1, whereinthe insulator includes a plurality of insulating members each havingopposite circumferential ends, with each insulating member correspondingto one of the core segments, and each insulating member being rotatablycoupled to an adjacent one of other insulating members by one of thecoupling portions at each of the circumferential ends of the insulatingmember.
 3. The insulator according to claim 2, wherein the insulatingmembers are formed separately from each other.
 4. The insulatoraccording to claim 3, wherein each insulating member has a couplingopening, which is formed on one of the circumferential ends of theinsulating member, and a coupling projection, which is formed on theother one of the circumferential ends of the insulating member, and eachcoupling portion is formed by the coupling projection of one of theadjacent insulating members being received by the coupling opening ofthe other one of the adjacent insulating members.
 5. The insulatoraccording to claim 4, wherein each coupling opening is an opening of athrough hole formed in each insulating member, the through hole has anotch, which extends in the radial direction, each coupling projectionhas a hook at the distal end of the coupling projection, and the hookextends in the radial direction.
 6. The insulator according to claim 4,wherein the coupling openings and the coupling projections arenon-circular as viewed from the direction of a relative rotational axisof the adjacent insulating members, and, when the core segments to whichinsulating members are attached are arranged in an annular form to formthe annular portion, the inner circumferential surface of each couplingopening partially contacts the outer circumferential surface of thecorresponding coupling projection.
 7. The insulator according to claim6, wherein a space is formed between the inner circumferential surfaceof each coupling opening and the outer circumferential surface of thecorresponding coupling projection in a direction orthogonal to therelative rotational axis, and, when the core segments to whichinsulating members are attached are rotated relative to one another froma state where the core segments are arranged in a straight line to astate where the core segments are arranged in an annular form, thesmallest portion of the space gradually reduces to zero.
 8. Theinsulator according to claim 3, wherein the insulating members includefirst insulating members and second insulating members, which arearranged alternately, each first insulating member includes couplingopenings, which are formed on the circumferential ends of the firstinsulating member, each second insulating member has couplingprojections, which are formed on the circumferential ends of the secondinsulating member, and each coupling portion between the adjacent firstand second insulating members is formed by one of the couplingprojections of the second insulating member being received by one of thecoupling openings of the first insulating member.
 9. The insulatoraccording to claim 8, wherein each coupling opening is an opening of athrough hole formed in each first insulating member, the through holehas a notch, which extends in the radial direction, each couplingprojection has a hook at the distal end of the coupling projection, andthe hook extends in the radial direction.
 10. The insulator according toclaim 9, wherein, when each adjacent pair of the first and secondinsulating members are located at a predetermined allowable anglerelative to each another, each hook permits the corresponding couplingprojection to be selectively inserted into and removed from thecorresponding through hole, and when the adjacent first and secondinsulating members are located at an angle other than the allowableangle, each hook prevents the corresponding coupling projection frombeing selectively inserted into and removed from the correspondingthrough hole.
 11. The insulator according to claim 2, wherein theinsulator is an integrally molded part, the adjacent insulating membersare integrally coupled to each other via one of the coupling portions,and the coupling portions are flexible.
 12. A stator for an electricrotating machine comprising: a plurality of core segments, wherein eachcore segment is formed by alternately laminating first piece members andsecond piece members, each core segment has an arcuate portion and atooth extending from the arcuate portion in a direction substantiallyorthogonal to the arcuate portion, each arcuate portion includesopposite circumferential ends, and when the core segments are arrangedin an annular form, the arcuate portions form the annular portion andthe teeth are arranged radially; an insulator attached to the pluralityof core segments; and a plurality of coils, with each coil wound aroundone of the teeth via the insulator, wherein each of the first and secondpiece members has a first end corresponding to one of thecircumferential ends of the arcuate portion and a second endcorresponding to the other one of the circumferential ends of thearcuate portion, the first piece member has an arcuate projection on thefirst end of the first piece member and an arcuate recess on the secondend of the first piece member, the second piece member has an arcuaterecess on the first end of the second piece member and an arcuateprojection on the second end of the second piece member, and when eachpiece member is viewed from the axial direction, the arcuate projectionforms an arcuate projection shape and the arcuate recess forms anarcuate recess shape, wherein, when the plurality of core segments arearranged in an annular form, the arcuate projections overlap one anotherat the adjacent circumferential ends of the arcuate portions, andwherein the insulator has a plurality of coupling portions at positionscorresponding to the circumferential ends of the arcuate portions, andwherein each coupling portion couples the adjacent core segments so asto be rotatable relative to each other.
 13. The stator according toclaim 12, wherein the insulator includes a plurality of insulatingmembers, each having opposite circumferential ends, with each insulatingmember corresponding to one of the core segments, and each insulatingmember being rotatably coupled to an adjacent one of other insulatingmembers by one of the coupling portions at each of the circumferentialends of the insulating member.
 14. The stator according to claim 13,wherein the insulating members are formed separately from each other.15. The stator according to claim 14, wherein each insulating member hasa coupling opening, which is formed on one of the circumferential endsof the insulating member, and a coupling projection, which is formed onthe other one of the circumferential ends of the insulating member, andeach coupling portion is formed by the coupling projection of one of theadjacent insulating members being received by the coupling opening ofthe other one of the adjacent insulating members.
 16. The statoraccording to claim 15, wherein each coupling opening is an opening of athrough hole formed in each insulating member, the through hole has anotch, which extends in the radial direction, each coupling projectionhas a hook at the distal end of the coupling projection, and the hookextends in the radial direction.
 17. The stator according to claim 15,wherein the coupling openings and the coupling projections arenon-circular as viewed from the direction of a relative rotational axisof the adjacent insulating members, and when the core segments to whichinsulating members are attached are arranged in an annular form to formthe annular portion, the inner circumferential surface of each couplingopening partially contacts the outer circumferential surface of thecorresponding coupling projection.
 18. The stator according to claim 17,wherein a space is formed between the inner circumferential surface ofeach coupling opening and the outer circumferential surface of thecorresponding coupling projection in a direction orthogonal to therelative rotational axis, and when the core segments to which insulatingmembers are attached are rotated relative to one another from a statewhere the core segments are arranged in a straight line to a state wherethe core segments are arranged in an annular form, the smallest portionof the space gradually reduces to zero.
 19. The stator according toclaim 14, wherein the insulating members include first insulatingmembers and second insulating members, which are arranged alternately,each first insulating member includes coupling openings, which areformed on the circumferential ends of the first insulating member, eachsecond insulating member has coupling projections, which are formed onthe circumferential ends of the second insulating member, and eachcoupling portion between the adjacent first and second insulatingmembers is formed by one of the coupling projections of the secondinsulating member being received by one of the coupling openings of thefirst insulating member.
 20. The stator according to claim 19, whereineach coupling opening is an opening of a through hole formed in eachfirst insulating member, the through hole has a notch, which extends inthe radial direction, each coupling projection has a hook at the distalend of the coupling projection, and the hook extends in the radialdirection.
 21. The stator according to claim 20, wherein, when eachadjacent pair of the first and second insulating members are located ata predetermined allowable angle relative to each another, each hookpermits the corresponding coupling projection to be selectively insertedinto and removed from the corresponding through hole, and when theadjacent first and second insulating members are located at an angleother than the allowable angle, each hook prevents the correspondingcoupling projection from being selectively inserted into and removedfrom the corresponding through hole.
 22. The stator according to claim13, wherein the insulator is an integrally molded part, the adjacentinsulating members are integrally coupled to each other via one of thecoupling portions, and the coupling portions are flexible.